Unique cortical physiology associated with ipsilateral hand movements and neuroprosthetic implications.
OBJECTIVE
Brain computer interfaces (BCIs) offer little direct benefit to patients with hemispheric stroke because current platforms rely on signals derived from the contralateral motor cortex (the same region injured by the stroke). For BCIs to assist hemiparetic patients, the implant must use unaffected cortex ipsilateral to the affected limb. This requires the identification of distinct electrophysiological features from the motor cortex associated with ipsilateral hand movements.


METHODS
In this study we studied 6 patients undergoing temporary placement of intracranial electrode arrays. Electrocorticographic (ECoG) signals were recorded while the subjects engaged in specific ipsilateral or contralateral hand motor tasks. Spectral changes were identified with regards to frequency, location, and timing.


RESULTS
Ipsilateral hand movements were associated with electrophysiological changes that occur in lower frequency spectra, at distinct anatomic locations, and earlier than changes associated with contralateral hand movements. In a subset of 3 patients, features specific to ipsilateral and contralateral hand movements were used to control a cursor on a screen in real time. In ipsilateral derived control this was optimal with lower frequency spectra.


CONCLUSIONS
There are distinctive cortical electrophysiological features associated with ipsilateral movements which can be used for device control. These findings have implications for patients with hemispheric stroke because they offer a potential methodology for which a single hemisphere can be used to enhance the function of a stroke induced hemiparesis.
Wisneski
Kimberly J
KJ
Department of Biomedical Engineering, Washington University in St Louis, MO, USA. kjw4@cec.wustl.edu
Anderson
Nicholas
N
Schalk
Gerwin
G
Smyth
Matt
M
Moran
Daniel
D
Leuthardt
Eric C
EC
D000293:Adolescent; D000328:Adult; D001186:Artificial Limbs; D001701:Bionics / Q000295:instrumentation; D001931:Brain Mapping; D002648:Child; D004292:Dominance, Cerebral; D004569:Electroencephalography; D005260:Female; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000502:physiology*; D009068:Movement / Q000502:physiology*; D010291:Paresis / Q000209:etiology / Q000534:rehabilitation*; D011474:Prosthesis Design; D011597:Psychomotor Performance / Q000502:physiology*; D020521:Stroke / Q000150:complications*; D014584:User-Computer Interface; D014836:Volition